1) Maintenance of the basic body posture - upright in humans and dorsal-side-up in quadrupeds - is a vital motor function. An efficient control of this posture is important for standing, walking, and for providing support of voluntary movements. Damage to spinal pathways caused by the spinal cord injury (SCI) results in a dramatic impairment of the postural system. Restoration of postural control is a necessary prerequisite for the recovery of other motor functions. The proposed study is devoted to characterization of the effects of SCI on the postural system in an animal model (rabbit). It will provide data on postural deficits caused by different types of SCI. (2) The SCI reduces or abolishes the supraspinal excitatory drive to the spinal postural network. Our aim is to re-activate this network and to restore spinal postural reflexes. This will be done by electrical or pharmacological stimulation of the cord below SCI. The efficacy of stimulation at different stages of SCI will be tested. These experiments will provide important insights into the nature of impairments of the spinal postural reflexes, and will characterize their potential for recovery in progressive stages of SCI. (3) Training of stepping or weight bearing in SCI subjects improve these motor functions. Our aim is to train specifically two major components of the postural system - the mechanism responsible for maintenance of limb/trunk configuration, and that generating postural reflex responses. These experiments will reveal optimal strategies for training in progressive stages of SCI, and provide suggestions for rehabilitation in human subjects. (4) The acute stage of SCI depends on many factors. Our aim is to clarify the effect on the activity of postural system produced by one of these factors - the termination of signal transmission in spinal pathways. This will be done by inactivation of spinal pathways caused by their cooling (reversible spinalization). These experiments will provide insights into the role of descending commands for activation of spinal postural mechanisms, and into the nature of postural dysfunction after SCI.